Method for encoding/decoding block information using quad tree, and device for using same

ABSTRACT

Disclosed decoding method of the intra prediction mode comprises the steps of: determining whether an intra prediction mode of a present prediction unit is the same as a first candidate intra prediction mode or as a second candidate intra prediction mode on the basis of 1-bit information; and determining, among said first candidate intra prediction mode and said second candidate intra prediction mode, which candidate intra prediction mode is the same as the intra prediction mode of said present prediction unit on the basis of additional 1-bit information, if the intra prediction mode of the present prediction unit is the same as at least either the first candidate intra prediction mode or the second candidate intra prediction mode, and decoding the intra prediction mode of the present prediction unit.

TECHNICAL FIELD

The present invention relates to a block information encoding/decodingmethod using a quad tree and an apparatus using the same, and moreparticularly, to a video encoding/decoding method.

BACKGROUND ART

Recently, with the expansion of broadcasting services having highdefinition (HD) resolution in the country and around the world, manyusers have been accustomed to a high resolution and definition video,such that many organizations have conducted many attempts to developnext-generation video devices. In addition, the interest in HDTV andultra high definition (UHD) having a resolution four times higher thanthat of HDTV have increased and thus, a compression technology forhigher-resolution and higher-definition video have been required.

For the video compression, an inter prediction technology predictingpixel values included in a current picture from a picture before and/orafter the current picture, an intra prediction technology predictingpixel values included in the current picture using pixel information inthe current picture, an entropy encoding technology allocating a shortcode to symbols having a high appearance frequency and a long code tosymbols having a low appearance frequency, or the like, may be used.

An example of the video compression technology may include a technologyproviding a predetermined network bandwidth under a limited operationenvironment of hardware, without considering a flexible networkenvironment. However, in order to compress video data applied to thenetwork environment in which the bandwidth is frequently changed, a newcompression technology is required. To this end, a scalable videoencoding/decoding method may be used.

DISCLOSURE Technical Problem

The present invention provides a method for decoding transform unitinformation using a quad tree so as to increase video encodingefficiency.

The present invention also provides a method for decoding transform unitinformation using a quad tree and a joint encoding method so as toincrease video encoding efficiency.

The present invention also provides an apparatus for decoding transformunit information using a quad tree so as to increase video encodingefficiency.

The present invention also provides an apparatus for decoding transformunit information using a quad tree and a joint encoding method so as toincrease video encoding efficiency.

Technical Solution

In an aspect, there is provided a method for decoding transform unitinformation using a quad tree structure, including: decoding integratedcode block flag information in a transform unit; and decoding a splitinformation flag based on size information and the integrated code blockflag information in the transform unit.

The decoding of the split information flag based on the size informationin the transform unit and the integrated code block flag information mayinclude: decoding the code block flag information in the transform unitwithout decoding the split information flag information when transformcoefficients are not present in the transform unit; and decoding thecode block flag information in the transform unit when the transformunit is not additionally split based on the split information flag.

The method for decoding transform unit information using a quad treestructure may further include decoding the code block flag informationin the transform unit without decoding the integrated code flag and thesplit information flag, when the size in the transform unit is the sameas a minimum transform unit that is not split into an additionaltransform unit.

The integrated code block flag may be applied only in a fixed transformdepth by fixing a transform depth, to which the integrated code blockflag is applied, to one or may be adapted at a plurality of transformunit depth by defining the transform depth by a predetermined parameter.

In another aspect, there is provided a method for decoding transformunit information using a quad tree structure, including: decodingpattern information in a transform unit based on a transform unitinformation joint flag in which an integrated code block flag and atransform information flag are joint and encoded; and decoding codeblock flag information and split information flag information in atransform unit corresponding to the pattern information based on thepattern information.

The pattern information may be variable generated based on the number ofcases in which the code block flag is present in a predeterminedtransform unit and the number of cases in which the split informationflag is present.

The pattern information may be binary-coded based on a table usingvariable length coding.

The pattern information may code the pattern information based on 4 bitinformation representing a luminance code block flag value by mostsignificant bit (MSB), a cb code block flag by MSB-1, a cr code blockflag by MSB-2, a spilt_flag by a least significant bit.

In another aspect, there is provided a video decoding apparatus,including: an entropy decoder decoding integrated code block flaginformation and size information in a transform unit and decoding asplit information flag and decoding transform coefficients in thetransform unit based on the integrated code block flag information andsize information in the transform unit; and an inverse transformerinversely transforming transform coefficient information in thetransform unit provided from the entropy decoder.

The entropy decoder may decodes the code block flag information in thetransform unit without decoding the split information flag informationwhen transform coefficients are not present in the transform unit; anddecode the code block flag information in the transform unit when thetransform unit is not additionally split based on the split informationflag.

The entropy decoder may decode the code block flag information in thetransform unit without decoding the integrated code flag and the splitinformation flag, when the size in the transform unit is the same as aminimum transform unit that is not split into an additional transformunit.

In another aspect, there is provided a video decoding apparatus,including: an entropy decoder decoding pattern information in atransform unit based on a transform unit information joint flag in whichan integrated code block flag and a transform information flag are jointand encoded and decoding code block flag information and splitinformation flag information in a transform unit corresponding to thepattern information based on the pattern information; and an inversetransformer inversely transforming transform coefficient information inthe transform unit provided from the entropy decoder.

The pattern information may be variable generated based on the number ofcases in which the code block flag is present in a predeterminedtransform unit and the number of cases in which the split informationflag is present.

The pattern information may be binary-coded based on a table usingvariable length coding.

The pattern information may code the pattern information based on 4 bitinformation representing a luminance code block flag value by mostsignificant bit (MSB), a cb code block flag by MSB-1, a cr code blockflag by MSB-2, a spilt_flag by a least significant bit.

Advantageous Effects

As set forth above, the block information encoding/decoding method usingthe quad tree and the apparatus using the same according to theexemplary embodiments of the present invention can represent thetransform coefficient information and the division possible informationin the current transform unit by using the integrated code flaginformation and the division information flag. Therefore, the exemplaryembodiments of the present invention can increase the encoding/decodingefficiency by encoding/decoding the transform coefficient informationand the division possible information in the transform unit using thesmaller bit.

DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a video encoding apparatus accordingto an exemplary embodiment of the present invention.

FIG. 2 is a block diagram showing a video decoder according to anotherexemplary embodiment of the present invention.

FIG. 3 is a flow chart showing a method for transmitting transform unitinformation using a quad tree structure according to another exemplaryembodiment of the present invention.

FIG. 4 is a conceptual diagram showing a method for applying anintegrated code block flag and a division information flag according toanother exemplary embodiment of the present invention.

FIG. 5 is a conceptual diagram showing a method for applying anintegrated code block flag and a division information flag according toanother exemplary embodiment of the present invention.

FIG. 6 is a conceptual diagram showing a method for applying anintegrated code block flag and a division information flag according toanother exemplary embodiment of the present invention.

FIG. 7 is a conceptual diagram showing a method for differently applyingan integrated code block flag and a division information flag accordingto another exemplary embodiment of the present invention depending ondepth information in a transform unit

FIG. 8 is a conceptual diagram showing a process of decoding transformunit information in a quad tree structure according to another exemplaryembodiment of the present invention.

FIG. 9 is a flow chart showing a method for encoding transformcoefficient information and division information in a transform unitwhen a transform unit information coupling flag is used.

FIG. 10 is a conceptual diagram showing a method for coupling andencoding an integrated code flag and a division information flagaccording to another exemplary embodiment of the present invention andintegrating transform unit information in transform units present at thesame depth.

MODE FOR INVENTION

Although the present invention can be modified variously and haveseveral embodiments, the exemplary embodiments are illustrated in theaccompanying drawings and will be described in detail in the detaileddescription. However, the present invention is not limited to thespecific embodiments and should be construed as including all thechanges, equivalents, and substitutions included in the spirit and scopeof the present invention.

Further, terms used in the specification, ‘first’, ‘second’, etc. can beused to describe various components, but the components are not to beconstrued as being limited to the terms. The terms are only used todifferentiate one component from other components. For example, thefirst component may be called the second component without departingfrom the scope of the present invention. Likewise, the second componentmay be called the first component. The term ‘and/or’ includes acombination of a plurality of items or any one of a plurality of terms.

In the case it is stated that any components are “connected” or“coupled” to other components, it is to be understood that thecomponents may be directly connected or coupled to other components, butthere is another component therebetween. On the other hand, in the casethat it is stated that any components are “directly connected” or“directly coupled” to other components, it is to be understood thatthere is no another component therebetween.

The terms used in the specification are used to describe only specificembodiments and are not intended to limit the present invention.Singular forms are intended to include plural forms unless the contextclearly indicates otherwise. It will be further understood that theterms “comprises” or “have” used in this specification, specify thepresence of stated features, steps, operations, components, parts, or acombination thereof, but do not preclude the presence or addition of oneor more other features, numerals, steps, operations, components, parts,or a combination thereof. Unless indicated otherwise, it is to beunderstood that all the terms used in the specification includingtechnical and scientific terms has the same meaning as those that areunderstood by those who skilled in the art. It must be understood thatthe terms defined by the dictionary are identical with the meaningswithin the context of the related art, and they should not be ideally orexcessively formally defined unless the context clearly dictatesotherwise.

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Indescribing the present invention, like components are denoted by likereference numerals in order to help in an overall understanding of thepresent invention and descriptions of the same or like components willnot be repeated.

FIG. 1 is a block diagram showing a video encoding apparatus accordingto an exemplary embodiment of the present invention.

Referring to FIG. 1, a video encoding apparatus 100 may include apicture splitter 105, a predictor 110, a transformer 115, a quantizer120, a realignment unit 125, an entropy encoder 130, a dequantizer 135,an inverse transformer 140, a filter unit 145, and a memory 150.

Each component shown in FIG. 1 are independently shown so as torepresent different characteristic functions in the video encodingapparatus and does not mean that each component is formed in separatedhardware or a single software configuration unit. In other words, eachconstitutional part includes each of enumerated constitutional parts forconvenience. Thus, at least two constitutional parts of eachconstitutional part may be joined to form one constitutional part or oneconstitutional part may be divided into a plurality of constitutionalparts to perform each function. The embodiment where each constitutionalpart is joined and the embodiment where one constitutional part isdivided are also included in the scope of the present invention, if notdeparting from the essence of the present invention.

In addition, some of constituents may not be indispensable constituentsperforming essential functions of the present invention but be selectiveconstituents improving only performance thereof. The present inventionmay be implemented by including only the indispensable constitutionalparts for implementing the essence of the present invention except theconstituents used in improving performance. The structure including onlythe indispensable constituents except the selective constituents used inimproving only performance is also included in the scope of the presentinvention.

The picture splitter 105 may split the input picture in at least oneprocessing unit. In this case, the processing unit may be a predictionunit (PU), a transform unit (TU), and an encoding unit (CU). The picturesplitter 105 may split a single picture in a joint of a plurality ofencoding units, prediction units, and transform units and may code thepictures by selecting a joint of the single encoding unit, theprediction unit, and the transform unit using a predetermined reference(for example, cost function).

For example, the single picture may be divided into the plurality ofencoding units. In order to split the encoding unit in the picture, arecursive tree structure such as a quad tree structure may be used. Theencoding unit split in other encoding units using a route as a singlevideo or a maximum size encoding unit may be split with children nodescorresponding to the number of split encoding units. The encoding unitthat is no more split according to a predetermined limitation becomes aleaf node. That is, the single encoding unit may be split in a maximumof four other encoding units if it is assumed that only a quadraticsplit is performed on a single encoding unit.

Hereinafter, in the exemplary embodiment of the present invention, ameaning of the encoding unit may be used as a meaning of the encodingunit as well as a meaning of the decoding unit.

The prediction unit may be split with shapes, such as at least onesquare, one rectangle, or the like, having the same size within thesingle encoding unit or a type in one of the split prediction unitswithin the single encoding unit may be split with a type different fromother prediction units.

When the prediction unit performing intra-picture prediction isgenerated based on the encoding unit, if it is assumed that theprediction unit is not the minimum encoding unit, an inter-pictureprediction may be performed without the encoding unit being spilt into aplurality of prediction units (N×N).

The predictor 110 may include an inter-picture predictor performing theinter-picture prediction and an intra-picture prediction performing theinter-picture prediction. It is possible to determine whether theinter-picture prediction is performed on the prediction unit or theintra-picture prediction is performed thereon and it is possible todetermine detailed information (for example, an intra-picture predictionmode, a motion vector, a reference picture, or the like) according toeach prediction method. In this case, a processing unit performing theprediction and a processing unit defining the prediction method and thedetailed contexts may be different from each other. For example, theprediction method, the prediction mode, or the like, may be determinedin the prediction unit and the prediction performance may also beperformed in the transform unit. A residual value (residual block)between the generated prediction block and an original block may beinput to the transformer 115. In addition, prediction mode information,motion vector information, or the like, used for prediction are encodedin the entropy encoder 130, together with the residual value, which maybe in turn transmitted to the decoder. When a specific encoding mode isused, it is possible to code the original block as it is withoutgenerating the prediction block through the predictor 110 and transmitthe encoded original block to the decoder.

The inter-picture predictor may predict the prediction unit based on atleast one picture information of pictures before and after the currentpicture. The inter-picture predictor may include a reference pictureinterpolator, a motion predictor, and a motion compensator.

The reference picture interpolator may receive reference pictureinformation from the memory 150 and may generate pixel information ofinteger pixels or less in the reference picture. In the case of aluminance pixel, in order to generate the pixel information of aninteger pixel or less in a ¼ pixel unit, a DCT-based 8 tap interpolationfilter having different filter coefficients may be used. In the case ofa chrominance pixel, in order to generate the pixel information of aninteger pixel or less in a ⅛ pixel unit, a DCT-based 4 tap interpolationfilter having different filter coefficients may be used.

The motion predictor may perform the motion prediction based on thereference picture interpolated by the reference picture interpolator. Asthe method for calculating the motion vector, various methods such asfull search-based block matching algorithm (FBMA), three step search(TSS), new three-step search algorithm (NTS), or the like, may be used.The motion vector may have a motion vector value in a ½ or ¼ pixel unitbased on the interpolated pixel. The motion predictor may predict thecurrent prediction unit by making the motion prediction methoddifferent. As the motion prediction method, various methods such as askip method, a merge method, an advanced motion vector prediction (AMVP)method, or the like, may be used.

The intra-picture predictor may generate the prediction unit based onthe reference pixel information around the current block that is thepixel information in the current picture. Since the peripheral blocks inthe current prediction unit are blocks performing the inter-pictureprediction, the reference pixel included in the block performing theinter-picture prediction may be replaced with the reference pixelinformation of the block performing the intra-picture predictiontherearound, when the reference pixel is a pixel subjected to theinter-picture prediction That is, when the reference pixel is not used,the non-used reference pixel information may be replaced with at leastone of the usable reference pixels.

In the intra-picture prediction, the prediction mode may include adirectional prediction mode using the reference pixel informationaccording to the prediction direction and a non-directional mode notusing the directional information at the time of performing theprediction. The mode for predicting the luminance information and themode for predicting the chrominance information may be different fromeach other and the intra-picture prediction mode information predictingthe luminance information so as to predict the chrominance informationor the predicted luminance signal information may be used.

When the size of the prediction unit and the size of the transform unitare the same at the time of performing the intra-picture prediction,even though the intra-picture prediction is performed on the predictionunit based on a pixel present at the left of the prediction unit, apixel present at the top left thereof, and a pixel present at the top,when the size of the prediction unit and the size of the transform unitis different from each other at the time of performing the intra-pictureprediction, the intra-picture prediction may be performed using thereference pixel based on the transform unit. In addition, theintra-picture prediction using N×N split may be performed on only theminimum encoding unit.

The intra-picture prediction method may generate the prediction blockafter an adaptive intra smoothing filter is applied to the referencepixel according to the prediction mode. The type of the AIS filterapplied to the reference pixel may be different. In order to perform theintra-picture prediction method, the intra-picture prediction mode ofthe current prediction unit may be predicted from the intra-pictureprediction mode in the prediction unit present around the currentprediction unit. When the prediction mode in the current prediction unitis predicted using the mode information predicted from the peripheralprediction unit and when the intra-picture prediction mode in thecurrent prediction unit and the peripheral prediction unit are the same,the information that the prediction mode in the current prediction unitand the peripheral prediction unit are the same may be transmitted usingthe predetermined flag information and when the prediction modes in thecurrent prediction unit and the peripheral prediction unit are differentfrom each other, the prediction mode information of the current blockmay be encoded using the entropy encoding.

In addition, the residual block including the residual information thatis a difference value between the prediction unit performing theprediction and the original block in the prediction unit may begenerated based on the prediction unit generated in the predictor 110.The generated residual block may be input to the transformer 115. Theresidual block including the original block and the residual informationin the prediction unit generated through the predictor 110 may betransformed using the transform method such as a discrete cosinetransform (DCT0 or a discrete sine transform (DST) in the transformer115. In order to transform the residual block, whether the DCT isapplied or the DST is applied may be determined based on theintra-picture prediction mode information in the prediction unit used soas to generate the residual block.

The quantizer 120 may quantize values transformed into a frequencydomain in the transformer 115. Quantization coefficients may be changedaccording to the block or the importance of video. The values calculatedin the quantizer 120 may be provided to the dequantizer 135 and therealignment unit 125.

The realignment unit 125 may perform the realignment of coefficientvalues for quantized residual values.

The realignment unit 125 may change two-dimensional block typecoefficients into one-dimensional vector type by a coefficient scanningmethod. For example, the realignment unit 125 may scan from DCcoefficients to coefficients in a high frequency domain by using azig-zag scan method to change the block type coefficients into theone-dimensional vector type. Rather than the zig-zag scan method, avertical scan method scanning the two-dimensional block typecoefficients in a column direction and a horizontal scan method scanningthe two-dimensional block type coefficients in a row direction may beused according to the size of the transform unit and the inter-pictureprediction mode. That is, whether any scan method of the zig-zag scan,the vertical direction scan, and the horizontal direction scan may bedetermined according to the size of the transform unit and theintra-picture prediction mode.

The entropy encoder 130 may perform the entropy encoding based on thevalues calculated by the realignment unit 125. For the entropy encoding,encoding methods such as exponential golomb, context-adaptive variablelength coding (CAVLC), context-adaptive binary arithmetic encoding(CABAC), or the like, may be used.

The entropy encoder 130 may code various information such as residualcoefficient information and block type information, prediction modeinformation, split unit information, prediction unit information,transmission unit information, motion vector information, referenceframe information, block interpolation information, filteringinformation, or the like, in the encoding unit from the realignment unit125 and the predictor 110.

The entropy encoder 130 may perform the entropy encoding on thecoefficient values in the encoding unit input from the realignment unit125.

The entropy encoder 130 may be stored with a table for performing theentropy encoding such as a variable length coding table and may performthe entropy encoding using the stored variable length coding table. Inperforming the entropy encoding, code word allocation for the codenumbers of the corresponding information to some code words included inthe table may be changed by using a counter using method or a directswapping method For example, in the case of several upper code numbersto which a smaller bit number of code words is allocated in the tablemapping the code numbers and the code words, a mapping sequence of thetable adaptively mapping the encoder words to the code numbers so as toallocate the code words of a short length to the code numbers in whichthe summed generation frequency of the code numbers is largest by usingthe counter may be changed. When the frequency counted in the counterreaches the predetermined threshold value, the counting may be againperformed by dividing the counting frequency written in the counter into½.

The position of the code numbers in the table that do not perform thecounting may be changed with the position of the code numbers just abovethe entropy encoding table using the direct swapping method when theinformation corresponding to the code number is generated. That is, thesmaller number of bits allocated to the corresponding code number in theentropy encoding table may be allocated.

The entropy encoder 130 may code the integrated code block flag at thecurrent transform depth and code the split information flag based on theintegrated code block flag information. In addition, the entropy encoder130 may join and code the split information flag based on the integratedcode block flag information. Hereinafter, the exemplary embodiment ofthe present invention will be described below with reference to theadditional encoding method.

The dequantizer 135 and the inverse transformer 140 inversely quantizethe quantized values in the quantizer 120 and inversely transform thevalues transformed in the transformer 115. The residual generated in thedequantizer 135 and the inverse transformer 140 may generate areconstructed block by being joined with the prediction unit predictedthrough a motion estimator, a motion compensator, and an intra predictorthat are included in the predictor 110.

The filter unit 145 may include at least one of a deblocking filter, anoffset compensator, and an adaptive loop filter (ALF).

The deblocking filter may remove block distortion generated due to aboundary between the blocks at the reconstructed picture. In order todetermine whether the deblocking is performed, it is possible todetermine whether the deblocking filter is applied to the current blockbased on the pixels included in several columns or rows included in theblock. When the deblocking filter is applied to the block, a strongfilter or a weak filter may be applied according to necessary deblockingfiltering strength. In addition, in applying the deblocking filter,horizontal direction filtering and vertical direction filtering at thetime of performing the vertical filtering and the horizontal filteringmay be processed in parallel.

The offset compensator may correct the offset with the original picturefor the video performing the deblocking in the pixel unit In order toperform the offset compensation for the specific picture, thepredetermined number of pixels included in the video is divided andthen, the region performing the offset is determined, and the method ofapplying the offset to the corresponding region and the method ofapplying the offset in consideration of the edge information each pixelmay be used.

The adaptive loop filter (ALF) may perform the filtering based on avalue obtained by comparing the filtered reconstructed picture and theoriginal picture. The filtering may be differently performed for eachgroup by dividing the pixel included in the video into the predeterminedgroup and then, determining a single filter to be applied to thecorresponding group. The information regarding whether the ALF isapplied may be transmitted for each encoding unit (CU) and the size andcoefficient of the ALF to be applied to each block may be changed. TheALF may have various type and thus, the number of coefficients includedthe filter may be changed. The filtering related information of the ALF(filter coefficient information, ALF on/off information, filter typeinformation) may be transmitted by being included in the predeterminedparameter set in the bit stream.

The memory 150 may store the reconstructed block or the picturescalculated through the filter unit 145, wherein the stored reconstructedblocks or pictures may be provided to the predictor 110 at the time ofperforming the inter-picture prediction.

FIG. 2 is a block diagram showing a video decoder according to anotherexemplary embodiment of the present invention.

Referring to FIG. 2, a video decoder 200 may include an entropy decoder210, a realignment unit 215, a dequantizer 220, an inverse transformer225, a predictor 230, a filter unit 235, and a memory 240.

In the video coder, when the video bit stream is input, the input bitstream may be decoded by a procedure reverse to the video coder.

The entropy decoder 210 may perform the entropy decoding by a procedurereverse to one performing the entropy encoding in the video coder. Forexample, in the video coder, the VLC table used to perform the entropyencoding is implemented by the same variable length coding table even inthe entropy decoder to perform the entropy decoding. The information forgenerating the prediction block among the decoded information in theentropy decoder 210 may be provided to the predictor 230 and theresidual performing the entropy decoding in the entropy decoder may beinput to the realignment unit 215.

Similar to the entropy encoder even in the entropy decoder 210, the codeword allocation table may be changed using the counter or the directswapping method and perform the entropy decoding based on the changedcode word allocation table.

The information regarding the intra-picture prediction and theinter-picture prediction performed in the encoder may be decoded. Asdescribed above, when there are predetermined limitations at the time ofperforming the intra-picture prediction and the inter-picture predictionin the video coder, the information regarding the intra-pictureprediction and the inter-picture prediction for the current block may beprovided by performing the entropy decoding based on the above-mentionedlimitations. The entropy decoder may perform the decoding operationdescribed in FIGS. 3 to 8 of the exemplary embodiment of the presentinvention.

The entropy decoder 210 may decode the integrated code block flaginformation in the transform unit and decode the split information flagbased on the size information and the integrated code block flaginformation in the transform unit. In addition, the pattern informationin the transform unit is decoded based on the transform unit informationcoupling flag encoded by coupling the integrated code block flag withthe transform information flag and the code block flag information andthe split information flag information in the transform unitcorresponding to the pattern information may be decoded based on thepattern information. The entropy decoding process will be described indetail in the following exemplary embodiment of the present invention.

The realignment unit 215 may perform the realignment based on a methodfor realigning bit streams, which are subjected to the entropy decodingin the entropy decoder 210, in the coder. The coefficients representedby the one-dimensional vector type may be again recovered into thecoefficients in the two-dimensional block type and realigned. Therealignment unit may perform the realignment by receiving informationrelating to the coefficient scanning performed in the encoder and amethod for reversely scanning the information based on the scanningsequence performed in the corresponding coder.

The dequantizer 220 may perform the dequantization based on thequantization parameter provided in the encoder and the realignedcoefficient values of the block.

The inverse transformer 225 may perform the DCT performed in thetransformer and the inverse DCT and the inverse DST on the DST withreference to the quantization results performed in the video coder. Theinverse transform may be performed based on the transmission unitdetermined in the video coder. The transformer of the video encoder mayselectively perform the DCT and the DST according to the predictionmethod and various information such as, the size and the predictiondirection of the current block, or the like, and the inverse transformer225 of the video decoder may perform the inverse transform based on thetransform information performed in the transformer of the video coder.

At the time of performing the transform, the transform may be performedbased on the encoding unit rather than the transform unit.

The predictor 230 may generate the prediction block based on theprediction block generation related information provided from theentropy decoder 210 and the previously decoded block or the pictureinformation provided from the memory 240.

As described above, similar to the operation in the video coder, whenthe size of the prediction unit and the size of the transform unit arethe same as each other at the time of performing the intra-picture, eventhough the intra-picture prediction is performed on the prediction unitbased on a pixel present at the left of the prediction unit, a pixelpresent at the top left thereof, and a pixel present at the top, whenthe size of the prediction unit and the size of the transform unit isdifferent from each other at the time of performing the intra-pictureprediction, the intra-picture prediction may be performed using thereference pixel based on the transform unit. In addition, theintra-picture prediction using N×N split may be performed on only theminimum encoding unit.

The predictor 230 may include a prediction unit determinator, aninter-picture predictor, and an intra-picture predictor. The predictionunit determinator may receive various information such as the predictionunit information input from the entropy decoder, the prediction modeinformation of the intra-picture prediction method, the motionprediction related information of the inter-picture prediction method,or the like, divide the prediction unit in the current encoding unit,and differentiate whether the prediction unit performs the inter-pictureprediction or the intra-picture prediction. The inter-picture predictormay perform the inter-picture prediction for the current prediction unitbased on the information included in at least one of the pictures beforeor after the current picture including the current prediction unit byusing the information necessary for the inter-picture prediction of thecurrent prediction unit provided from the video coder.

In order to perform the inter-picture prediction, it is possible todetermine whether the motion prediction method of the prediction unitincluded in the corresponding encoding unit may corresponds to any oneof a skip mode, a merge mode, and an AMVP mode based on the encodingunit.

The intra-picture predictor may generate the prediction block based onthe pixel information within the current picture. When the predictionunit is a prediction unit performing the intra-picture prediction, theintra-picture prediction may be performed based on the intra-picturemode information of the prediction unit provided from the video coder.The intra-picture predictor may include an AIS filter, a reference pixelinterpolator, and a DC filter. The AIS filter, which is a partperforming the filtering on the reference pixel of the current block,may be applied by determining whether the filter is applied according tothe prediction mode of the current prediction unit. The AIS filteringmay be performed on the reference pixel of the current block by usingthe prediction mode of the prediction unit and the AIS filterinformation provided from the video coder. When the prediction mode ofthe current block is a mode that does not perform the AIS filtering, theAIS filter may not be applied.

The reference pixel interpolator may generate the reference pixel in thepixel unit of the integer value or less by interpolating the referencepixel when the prediction mode of the prediction unit is the predictionunit performing the intra-picture prediction based on the pixel valueinterpolating the reference pixel. When the prediction mode of thecurrent prediction unit is the prediction mode generating the predictionblock without interpolating the reference pixel, the reference pixel maynot be interpolated. The DC filter may generate the prediction blockthrough the filtering when the prediction mode of the current block isthe DC mode.

The reconstructed block or picture may be provided to the filter unit235. The filter unit 235 may include a deblocking filter, an offsetcompensator, and ALF.

The information regarding whether the deblocking filter is applied tothe corresponding block or the picture from the video encoder and if itis determined that the deblocking filter is applied, the informationregarding whether the strong filter is applied or the weak filter isapplied may be provided. The deblocking filter of the video decoder mayreceive the deblocking filter related information provided from thevideo encoder and may perform the deblocking filtering on thecorresponding block in the video decoder. Similar to the video coder,the vertical deblocking filtering and the horizontal deblockingfiltering are first performed but any one of the vertical deblocking andthe horizontal deblocking may be performed in the overlapping portion.The vertical deblocking filtering or the horizontal deblocking filteringthat is not previously performed at the overlapping portion where thevertical deblocking filtering and the horizontal deblocking filteroverlap each other may be performed. It is possible to perform parallelprocessing of the deblocking filtering through the deblocking filteringprocess.

The offset compensator may perform the offset compensation on thereconstructed picture based on the type of the offset compensation, theoffset value information, or the like, applied to the picture at thetime of the encoding.

The ALF may perform the filtering based on the value obtained bycomparing the reconstructed picture after the filtering is performed andthe original picture. The ALF may be applied to the encoding unit basedon the information regarding whether the ALF is applied, the ALFcoefficient information, or the like, that are provided from the coder.The ALF information may be provided by being included in the specificparameter set.

The memory 240 may store the reconstructed picture or the block so as tobe used as the picture or the reference block and may also provide thereconstructed picture to an output unit.

As described above, in the exemplary embodiment of the presentinvention, the encoding unit is used as a term to be the encoding unitfor convenience of explanation, but may be the unit performing theencoding as well as the decoding. Hereinafter, the encoding/decodingmethod of the intra-picture prediction mode using two candidate intraprediction modes described in FIGS. 3 to 12 according to the exemplaryembodiment of the present invention may be performed so as to meetfunctions of each module described in FIGS. 1 and 2. The encoder anddecoder are included in the scope of the present invention.

Hereinafter, a binary code representing the predetermined flaginformation used in the exemplary embodiment of the present invention isonly by way of example and therefore, the same information may berepresented by different binary codes, which is included in the scope ofthe present invention.

FIG. 3 is a flow chart showing a method for transmitting transform unitinformation using a quad tree structure according to another exemplaryembodiment of the present invention.

Referring to FIG. 3, it is determined whether the size of the currenttransform unit is larger than a minimum transform unit (S300).

The size of the current transform unit may be calculated based oncoefficients representing transform depth information (trafoDepth), sizeinformation in a maximum transform unit or may directly be calculatedthrough coefficients representing block size information.

The integrated code block flag information is transmitted only when thesize of the current transform unit is larger than the minimum transformunit and does not transmit the integrated code block flag informationwhen the size of the current transform unit is the size of the minimumtransform unit, each code block flag cbf_y, cbf_u, and cbf_v mayimmediately be encoded in the current transform unit (S340).

The code block flag cbf_luma or cbf_y may represent whether at least onetransform coefficient rather than 0 among the transform coefficientvalues transforming the luminance signals is present in the currenttransform unit, cbf_cb may represent whether at least one transformcoefficient rather than 0 among the transform coefficient valuestransforming the chrominance signal cb is present in the currenttransform unit, and cbf_cr may represent whether at least one transformcoefficient rather than 0 among the transform coefficient valuestransforming the chrominance signal cr is present in the currenttransform unit.

When the size of the current transform unit is larger than the minimumtransform unit, the integrated code block flag is encoded at the currenttransform depth (S310).

The integrated code block flag, is a flag representing whether thetransform quantization coefficients of the luminance signal and thechrominance signal are present, means that at least one transformcoefficient rather than 0 is present in the corresponding transform unitwhen the integrated code block flag is not 0.

The integrated code flag may be used as the flag representativelyrepresenting the Y/Cb/Cr code block flag. If any one of cbfs of Y/Cb/Cris not 0, the integrated code flag may be represented by a value ratherthan 0 and if all of cbfs of Y/Cb/Cr are 0, the integrated code flag maybe represented by 0.

Whether the fixed depth used by the integrated code block flag isapplied to various units such as sequence, picture, slice, or the like,may be changed by fixedly defining the transform depth used by theintegrated code block flag in advance or adaptively changing thetransform depth to which the integrated code block flag may be applied.The information for adaptively changing the transform depth may beincluded in a sequence parameter set (SPS), a picture parameter set(PPS), and a slice header.

The split information flag is phase-coded at the current transform depthaccording to the integrated code block flag information (S320).

The information regarding whether the current transform unit is splitmay be transmitted through context element split_transform_flag.Hereinafter, in the exemplary embodiment of the present invention, thesplit information flag may be used as the same meaning assplit_transform_flag.

For example, when the current transform unit is split, the value of thesplit information flag is set to be values rather than 0 and when thecurrent transform unit is not split, the value of the split informationflag may be set to be 0. The context element and the binary code forrepresenting the context element information used in the exemplaryembodiment of the present invention is only by way of an example andtherefore, another context element and the binary code of anothercontext element may be used unless they are in the scope of the presentinvention.

In the block information transmission method using the quad treeaccording to the exemplary embodiment of the present invention, thesplit information may be differently transmitted according to theintegrated code flag.

When the integrated code block flag is not 0 and the current transformunit is not split into the lower transform unit, the integrated codeblock flag has 0 as the split information flag and when the integratecode block flag is not 0 and the current transform unit is split intothe lower transform unit, the integrated code block flag may have thevalue rather than 0 as the split information flag value. In addition,when the integrated code block flag is 0, the unnecessary splitinformation may not be transmitted by not additionally transmitting thesplit information for the current transform unit. Joint encoding may beperformed by joining the integrated code block fag and the splitinformation flag. When the integrated code block flag and the splitinformation flag is joint-coded, procedures of steps S300 to S320 may bechanged. When the integrated code block flag is applied, the encodingmethod determines what information among cbf_y, cbf_u, cbf_v, andsplit_flag needs to be encoded in the current transform unit and then,represents the split_transform_flag by the predetermined patterninformation and may represent each of the code block flag cbf_y, cbf_u,and cbf_v and the split information flag split_transform_flag in thecurrent transform unit based on the pattern information. The encodingmethod using the integrated code flag will be described in more detailbelow.

It is determined whether the current transform unit is additionallysplit (S330).

When the transform unit is additionally split, it is determined whetherthe size of the split transform unit by returning to S300 is thetransform unit of the minimum size and if it is determined that thesplit transform unit is the transform unit of the minimum size, aprocedure for encoding the transform unit information may be ended afterimmediately converting the transform coefficient information cbf_y,cbf_u, and cbf_v each present in the transform unit without transmittingthe integrated code block flag information by returning to step S340.

Hereinafter, a method for transmitting the integrate code block flag andthe split information flag based on the encoding unit will be describedwith reference to FIGS. 4 to 6. That is, the transform coefficientinformation in the transform unit and the split information included inthe encoding unit may be transmitted for each unit. However, in theblock information transmitting method using a tree according to theexemplary embodiment of the present invention may transmit theintegrated code block flag and the split information flag for eachtransform unit.

FIG. 4 is a conceptual diagram showing a method for applying anintegrated code block flag and a division information flag according toanother exemplary embodiment of the present invention.

Referring to FIG. 4, the top end of FIG. 4 and the bottom end of FIG. 4are an all zero coefficient block (AZCB) in which the transformcoefficient included in the current transform unit is not present andwhen the integrated code block flag is applied to only the uppermosttransform block, FIG. 4 shows a conceptual diagram of the method fortransmitting the integrated code block flag and the split informationflag.

Hereinafter, in the exemplary embodiment of the present invention, theall zero coefficient block (AZCB) in which the transform coefficient isnot in the current transform unit may be represented by a term calledthe zero transform coefficient transform unit.

The top end of FIG. 4 shows the case in which the size of the encodingunit is the same as the size of the uppermost transform unit and thecase in which the transform coefficient included in the transform unitis not present.

When the size of the encoding unit is the same as the size of theuppermost transform unit and the transform coefficient included in thetransform unit is not present, additional split is not performed. As aresult, the integrated code block flag is set to be 0 in the uppermosttransform unit and the size information of the current transform unitand the transform coefficient information may be transmitted withouttransmitting the split information flag.

That is, in the block information transmitting method using the quadtress according to the exemplary embodiment of the present invention,since the zero transform coefficient transform unit in which thetransform coefficient is not present is not split in the additionaltransform unit and therefore, the split information is not unnecessary,such that the split information flag is not additionally transmitted.

The bottom end of FIG. 4 shows the case in which the size of theencoding unit is different from the size of the uppermost transform unitand the case in which the transform coefficient included in thetransform unit is not present.

When the size of the uppermost transform unit is smaller than theencoding unit and the uppermost transform unit included in the encodingunit is the all zero transform coefficient transform unit, theintegrated code block flag is set to be 0 and the size information ofthe current transform unit and the transform coefficient information maybe transmitted without transmitting the split information flag.

FIG. 5 is a conceptual diagram showing a method for applying anintegrated code block flag and a division information flag according toanother exemplary embodiment of the present invention.

When the top end and the bottom end of FIG. 5 are provided with thetransform coefficient included in the current transform unit and theintegrated code block flag is applied to only the uppermost transformblock, FIG. 5 is a conceptual diagram showing the method fortransmitting the integrated code flag and the split information flag.

The top end of FIG. 5 shows the case in which the size of the encodingunit is the same as the size of the uppermost transform unit and thecase in which the uppermost transform coefficient is not split into theadditional transform unit while the transform coefficient being present.

The integrated code block flag is set to be a value rather than 0 in theuppermost transform unit and the split information flag is transmittedas 0, thereby transmitting the information regarding whether the currenttransform unit is split and the transform coefficient information.

The bottom end of FIG. 5 shows the case in which the size of theencoding unit is the same as the size of the uppermost transform unitand the case in which the uppermost transform unit is split into theadditional transform unit while the transform coefficient being present.

When the size of the uppermost transform unit is the same as the size ofthe encoding unit and at least on of the lower split transform units isa block in which the transform coefficient is present, the integratedcode flag is set to be a value rather than 0 in the uppermost transformunit and the split information flag is transmitted as a value ratherthan 0 and as a result, whether the transform coefficient is present inthe transform unit included in the current encoding unit and the splitstate may be represented.

FIG. 6 is a conceptual diagram showing a method for applying anintegrated code block flag and a division information flag according tostill yet another exemplary embodiment of the present invention.

FIG. 6 shows the case in which the size of the uppermost transform unitis smaller than the encoding unit and the transform coefficient ispresent.

When the size of the uppermost transform unit is smaller than theencoding unit and the transform coefficient is present, since theintegrated code block flag is transmitted as a value rather than 0 andis split into the transform unit having the smaller size that thecurrent encoding unit, the split information of the transform unitincluded in the current encoding unit may be represented withouttransmitting the split information flag.

FIG. 7 is a conceptual diagram showing a method for differently applyingan integrated code block flag and a division information flag accordingto another exemplary embodiment of the present invention depending ondepth information in a transform unit.

In FIG. 7, the integrated code block flag and the split information flagmay be transmitted based on the transform unit.

The top end of FIG. 7 shows the case in which the depth of the transformunit is 0, that is, the integrated code flag is applied to only theuppermost transform unit.

When the depth of the transform unit is 0, the integrated code blockflag and the split information flag are applied to only the uppermostencoding unit, the integrated code block flag may be transmitted basedon whether the transform coefficient is present in the upper transformunit based on the uppermost transform unit and the split informationflag regarding whether the uppermost transform unit is additionallysplit may be transmitted. In the case of the top end of FIG. 7, sincethe transform coefficient is present based on the uppermost transformunit, the integrated code block flag may be set to be a value ratherthan 0 (cbf_yuv[depth]!=0) and the split information flag may be set tobe 1 (split_transform_flag[depth]!=0).

The bottom end of FIG. 7 show the case in which the integrated codeblock flag and the split information flag is applied up to depth 1 ofthe transform unit.

In the bottom block of FIG. 7, when the depth of the transform unit is0, since the transform coefficient is present, the integrated code blockflag may be set to be a value rather than 0 and since the transformcoefficient is split into the additional lower transform unit, the splitinformation flag may be set to be 1.

When the transform depth is 1, the integrated code flag and the splitinformation flag may again be applied to each transform unit. Forexample, when a first transform unit 700, a second transform unit 710, athird transform unit 720, and a fourth transform unit 730 are set basedon a Z scan direction, the first transform unit 700 to the thirdtransform unit 720 does not include the transform coefficient andtherefore, the integrated code block flag is transmitted as 0 and allthe transform coefficients are 0 and therefore, is not split into theadditional coefficient unit, such that the split information flag maynot be transmitted (cbf_yuv[depth]=0, split_transform_flag[depth]=0).Since the fourth transform unit 730 includes the transform coefficientand is additionally split into the transform unit, the integrated codeflag is transmitted as a value rather than 0 and the split informationflat may be transmitted as 1 (cbf_yuv[depth]!=0,split_transform_flag[depth]!=0).

The following Table 1 shows a context transmitting the integrated codeflag and the split information flag.

TABLE 1 transform_tree {  cbf_yuv (Depth)   split_transform_flag (Depth)        ... ... ...

Referring Table 1, the integrated code block flag and the splitinformation flag may be represented in the transform tree syntaxaccording to the transform unit depth information.

FIG. 8 is a conceptual diagram showing a process of decoding transformunit information in a quad tree structure according to another exemplaryembodiment of the present invention.

The transform unit disclosed at the left of FIG. 8 shows the case inwhich the size of the maximum transform unit is 32×32 and the size ofthe minimum transform unit is 4×4.

The left of FIG. 8 is a block showing the split state in the currenttransform unit and whether the transform coefficient is present and theright of FIG. 8 shows a tree structure showing a method for representingthe integrated code block flag and the split information flag,respectively, at each depth of the transform unit.

FIG. 8 shows the case in which cbf_yuv_flag is a value rather than 0 andthe transform coefficient is present at the transform unit depth 0, whenthe transform depth is 0 800 and the split_transform_flag is 1 and meansthat the spilt is performed in the lower transform unit.

FIG. 8 shows the information regarding whether the transform coefficientis present in the transform unit split into the transform unit depth 1and whether the transform unit of the transform unit depth 1 isadditionally split, when the transform depth is 1 810, 820, 830, and840. That is, the first transform block 850 transmits 0 as the value ofthe integrated code block flag and does not additionally transmit thesplit information flag since the transform coefficient is not present.The fourth transform block 860 is the same as the first transform blockand the second transform block 870 and the third transform block 880transmit the integrated code block flag as the value rather than 0 sincethere is the transform coefficient and may transmit the splitinformation flag as 1 since the integrated code block flag is split intothe additional transform unit.

Considering the additionally split transform unit based on the secondtransform block, the current transform unit is not additionally split880, each of the cbf_y, cbf_u, and cbf_v may be transmitted and when thecurrent transform unit is additionally split 890, the integrated codeblock flag information and the split information flag may be transmittedin the current transform unit.

When the additionally split transform unit is the minimum transform unit895, the cbf_y, cbf_u, and cbf_v information in the minimum unit may beimmediately transmitted.

As described above, in the block information transmitting method usingthe quad tree according to another exemplary embodiment of the presentinvention and the apparatus using the method, the integrated code blockflag and the split information flag may be joined and encoded.

When a joint of the integrated code block flag and the split informationflag is patterned and encoded, the same information may be transmittedat smaller bit values, rather than encoding each of split_transform_flagrepresenting the cbf_y, cbf_u, and cbf_v and the split information thatis each component of the integrated code block flag. When the jointencoding is used, cbf_y, cbf_u, and cbf_v that are each component of theintegrated code block flag and split_transform_flag informationrepresenting the split information may be joined and encoded.

cbf_yuv_split_flag joined and encoded by each component, that is, cbf_y,cbf_u, cbf_v, that may calculate the integrated code block flag with thesplit_transform_flag information may be represented by a single contextelement and the term, the transform unit information joint flag is usedas the same meaning as the cbf_yuv_split_flag.

The following Table 2 is a table for performing the joint encoding fortransmitting a joint of the integrated code flag and the splitinformation flag.

TABLE 2 Pattern No. cbf_y cbf_y cbf_y splitflag Code Word 1 1 0 0 0 1 21 0 0 1 10 3 1 1 0 0 110 4 1 1 0 1 1110 5 1 1 1 0 11110 6 1 1 1 1 111110. . . . . . . . . . . . . . . . . .

Referring to FIG. 2, the case in which cbf_y, cbf_u, and cbf_v that areeach component of the integrated code block flag and thesplit_transform_flag representing the split information may be outputmay be defined by a single table. For example, the transform unitinformation joint flag may code the case in which each component, thatis, cbf_y, cbf_u, and cbf_v of the integrated code block flag and thesplit_transform_flag representing the split information may be outputbased on the pattern information.

For example, in the transform unit of the upper unit, when the cbf_u andthe cbf_v are encoded in advance, the cbf_u and the cbf_v informationdoes not need to be encoded in the lower transform unit and when thecurrent transform unit is the minimum encoding unit, only the cbf_yneeds to be encoded. In this case, only the information regardingwhether the luminance signal is present in the current transform unitthrough pattern 1 may be encoded. That is, the pattern in the currenttransform unit is 1 and the information regarding whether the luminancesignal is additionally present in the current transform unit may betransmitted.

As another example, in the transform unit of the upper unit, the cbf_uand the cbf_v are encoded in advance and when the current transform unitis not the transform unit of the minimum size, the information regardingwhether the luminance signal is present in the current transform unitbased on pattern 2 may be encoded. That is, the pattern in the currenttransform unit is 2 and the information regarding whether the luminancesignal in the current transform unit is present and whether the currenttransform unit is split may be transmitted.

Only the corresponding information may be encoded by determining whatinformation is required to code in the current transform unit throughthe method using the pattern. The pattern information may be firstrepresented by the 4 bit information representing a cbf-y value by MSB,a cbf-u by MSB-1, cbf-v by MSB-2, and split_flag by LSB and the flagpattern may also be subjected to binary encoding using the VLC code atthe time of being encoded later.

The following Table 3 shows a syntax structure of the transform unitinformation joint flag that joins and encodes the integrated code flagwith the split information flag.

TABLE 3 transform_tree {        ... ... ...  cbf_yuv_split_trans (Depth)       ... ... ...

Referring to FIG. 3, the luminance signal information, the chrominancesignal information, and the split information may be represented in theencoding unit by adding a cbf_yuv_split_trans that is a new contextelement to a transform_tree context.

In the block information transmitting method using the quad treeaccording to another exemplary embodiment of the present invention mayjoin and code once the transform unit information joint flag of thetransform units having the same size present at the same depth.

FIG. 9 is a flow chart showing a method for encoding transformcoefficient information and division information in a transform unitwhen a transform unit information coupling flag is used.

Referring to FIG. 9, a pattern of the code block flag and the splitinformation flag to perform the encoding in the transform unit areencoded (S900).

The pattern information on the code block flag and the split informationflag may be encoded based on Table 2.

The corresponding code block flag and the split information flag areencoded based on the encoded pattern information (S910).

The values of the code block flag and the split information flagcorresponding to the corresponding pattern information are encoded basedon the encoded pattern information.

For example, when the pattern information is 2, the informationregarding whether the luminance signal is present in the currenttransform unit may be encoded.

FIG. 10 is a conceptual diagram showing a method for coupling andencoding an integrated code flag and a division information flagaccording to another exemplary embodiment of the present invention andintegrating transform unit information in transform units present at thesame depth.

Referring to FIG. 10, each block represents the transform unit andnumbers listed on each transform unit means the pattern information onthe joint flag information. For convenience, 0 in the block and Tabledescribed below means pattern 1, pattern 1 means pattern 2, and pattern3 means pattern 4.

Referring to the left of FIG. 10, the transform unit consists of fourtransform units that is pattern information 1 and referring to the rightof FIG. 10, the transform unit consists of four transform units that are2, 4, 2, and 1.

That is, the single upper transform unit pattern information may begenerated by again joining the pattern information of the lowertransform unit in the upper transform unit. The following Table 4 is aTable representing the upper transform unit pattern information.

TABLE 4 cbf_yuv_split_flag First First First First Pattern TransformTransform Transform Transform Code No. Unit Unit Unit Unit Word 1 0 0 00 1 2 1 1 1 1 10 3 1 1 1 2 110 4 1 1 0 3 1110 5 1 3 1 0 11110 6 3 1 3 1111110 . . . . . . . . . . . . . . . . . .

Referring to Table 4, in the case of the transform unit present in theleft of FIG. 8, number 1 transform unit may have a pattern value ofcbf_yuv_split_trans of 0, number 2 transform unit may have a patternvalue of cbf_yuv_split_trans of 0, number 3 transform unit may have apattern value of cbf_yuv_split_trans of 0, and number 4 transform unitmay have a pattern value of cbf_yuv_split_trans of 0 in a z scandirection and may also have new pattern information 1. In the case ofthe transform unit present in the left of FIG. 10, number 1 transformunit may have a pattern value of cbf_yuv_split_trans of 1, number 2transform unit may have a pattern value of cbf_yuv_split_trans of 3,number 3 transform unit may have a pattern value of cbf_yuv_split_transof 1, and number 4 transform unit may have a pattern value ofcbf_yuv_split_trans of 5.

The upper transform block pattern information may also be used by beingdefined as the new context element in the transform tree context.

FIG. 11 is a flow chart for decoding the block information having thequad tree structure according to another exemplary embodiment of thepresent invention.

Referring to FIG. 11, the integrated code block flag information in thecurrent transform unit is decoded (S1100).

The split information flag is decoded based on the size information ofthe current transform unit and the integrated code flag information(S1110).

When the transform unit information joint flag cbf_yuv_split_flag inwhich the above-mentioned integrated code block flag with thesplit_transform_flag are joined is used, processes of S1100 and S1110may be changed. As described in Table 2, the transform unit informationjoint flag information in the current transform unit is decoded and theinformation regarding whether the luminance signal and the chrominancesignal are present in the current transform unit or spilt based on thedecoded pattern information may be additionally decoded.

FIG. 12 is a flow chart showing a method for decoding transform unitinformation joint flag information according to another exemplaryembodiment of the present invention.

Referring to FIG. 12, the pattern information is decoded based on thetransform unit information joint flag information (S1200).

The code block flag or the split information flag informationcorresponding to the pattern are decoded based on the decoded patterninformation (S1210).

That is, the pattern information is provided based on theabove-mentioned Table 2 and the code block flag information and thesplit information flag information corresponding to the correspondingpattern information may be decoded.

While the present invention has been shown and described in connectionwith the embodiments, it will be apparent to those skilled in the artthat modifications and variations can be made without departing from thespirit and scope of the invention as defined by the appended claims.

1. A method for decoding transform unit information using a quad treestructure, comprising: decoding integrated code block flag informationin a transform unit; and decoding a split information flag based on sizeinformation and the integrated code block flag information in thetransform unit.
 2. The method of claim 1, wherein the decoding of thesplit information flag based on the size information in the transformunit and the integrated code block flag information includes: decodingthe code block flag information in the transform unit without decodingthe split information flag information when transform coefficients arenot present in the transform unit; and decoding the code block flaginformation in the transform unit when the transform unit is notadditionally split based on the split information flag.
 3. The method ofclaim 1, further comprising decoding the code block flag information inthe transform unit without decoding the integrated code flag and thesplit information flag, when the size in the transform unit is the sameas a minimum transform unit that is not split into an additionaltransform unit.
 4. The method of claim 1, wherein the integrated codeblock flag uses a quad tree structure that is an integrated code blockflag that is applied only in a fixed transform depth by fixing atransform depth, to which the integrated code block flag is applied, toone or an integrated code block flag that is applied at a plurality oftransform unit depth by defining the transform depth by a predeterminedparameter.
 5. A method for decoding transform unit information using aquad tree structure, comprising: decoding pattern information in atransform unit based on a transform unit information joint flag in whichan integrated code block flag and a transform information flag are jointand encoded; and decoding code block flag information and splitinformation flag information in a transform unit corresponding to thepattern information based on the pattern information.
 6. The method ofclaim 5, wherein the pattern information is variable generated based onthe number of cases in which the code block flag is present in apredetermined transform unit and the number of cases in which the splitinformation flag is present.
 7. The method of claim 5, wherein thepattern information is binary-coded based on a table using variablelength coding.
 8. The method of claim 5, wherein the pattern informationencodes the pattern information based on 4 bit information representinga luminance code block flag value by most significant bit (MSB), a cbcode block flag by MSB-1, a cr code block flag by MSB-2, a spilt_flag bya least significant bit (LSB).
 9. A video decoding apparatus,comprising: an entropy decoder decoding integrated code block flaginformation and size information in a transform unit and decoding asplit information flag and decoding transform coefficients in thetransform unit based on the integrated code block flag information andsize information in the transform unit; and an inverse transformerinversely transforming transform coefficient information in thetransform unit provided from the entropy decoder.
 10. The video decodingapparatus of claim 9, wherein the entropy decoder decodes the code blockflag information in the transform unit without decoding the splitinformation flag information when transform coefficients are not presentin the transform unit; and decodes the code block flag information inthe transform unit when the transform unit is not additionally splitbased on the split information flag.
 11. The video decoding apparatus ofclaim 9, wherein the entropy decoder decodes the code block flaginformation in the transform unit without decoding the integrated codeflag and the split information flag, when the size in the transform unitis the same as a minimum transform unit that is not split into anadditional transform unit.
 12. A video decoding apparatus, comprising:an entropy decoder decoding pattern information in a transform unitbased on a transform unit information joint flag in which an integratedcode block flag and a transform information flag are joint and encodedand decoding code block flag information and split information flaginformation in a transform unit corresponding to the pattern informationbased on the pattern information; and an inverse transformer inverselytransforming transform coefficient information in the transform unitprovided from the entropy decoder.
 13. The video decoding apparatus ofclaim 12, wherein the pattern information is variable generated based onthe number of cases in which the code block flag is present in apredetermined transform unit and the number of cases in which the splitinformation flag is present.
 14. The video decoding apparatus of claim12, wherein the pattern information is binary-coded based on a tableusing variable length coding.
 15. The video decoding apparatus of claim12, wherein the pattern information encodes the pattern informationbased on 4 bit information representing a luminance code block flagvalue by most significant bit (MSB), a cb code block flag by MSB-1, a crcode block flag by MSB-2, a spilt_flag by a least significant bit (LSB).